This invention pertains to thermally reforming a heavy naphthenic compound tetra-hydro-dicyclo-penta-diene (THDCPD) dissolved in a suitable solvent material to produce benzene product. It pertains particularly to such a process for thermal reforming feedstocks containing the naphthenic compound THDCPD together with alkyl aromatic materials and simultaneously hydrodealkylating the aromatic materials to produce mainly benzene, along with only minor amounts of heavy multi-ring aromatic materials and gas by-products.
When hydrodealkylating heavy aromatic feedstocks including those containing appreciable amounts of THDCPD together with C.sub.9 and C.sub.10 mono-aromatic materials to yield mainly benzene product, it has been customary to minimize THDCPD compounds in the feedstock by a distillation step before the hydrodealkylation. At thermal hydrodealkylation reaction conditions, any naphthenes present in the feedstock would be expected to result in producing gas products such as methane and ethane and consume considerable hydrogen and also produce heavy multi-ring aromatics materials normally of little value. However, it has now been unexpectedly found that hydrocarbon feedstocks containing tetra-hydro-dicyclo-penta-diene (THDCPD) dissolved in alkyl aromatic fractions, can be simultaneously thermally reformed and hydrodealkylated successfully in a plug flow type non-catalytic reactor to produce significant yields of benzene product by utilizing a critical range of thermal reaction conditions. The reforming of the naphthenic THDCPD material and the simultaneous reforming and hydrodealkylation of THDCPD containing alkyl aromatic feedstocks to produce benzene were achieved during experimental work intended to process C.sub.9.sup.+ heavy aromatic feedstock containing THDCPD in a hydrodealkylation (HDA) reactor unit to produce benzene product. This discovery advantageously permits processing heavy aromatic feedstocks containing the heavy naphthenic compound THDCPD, by utilizing existing hydrodealkylation process technology to produce additional benzene product without removing the naphthenic material from the feedstock. It is believed there is no prior art for reforming THDCPD to produce aromatics like benzene and toluene in a non-catalytic thermal reactor.